Re-learning gdi+[90]: Tgpimage (10)

This example effect chart:

Code files:Unit Unit1;
Interface
Uses
Windows, Messages, sysutils, variants, Classes, Graphics, Controls, Forms,
Dialogs, Stdctrls, Grids;
Type
TForm1 = Class (Tform)
Drawgrid1:tdrawgrid;
Opendialog1:topendialog;
Button1:tbutton;
Procedure Formcreate (Sender:tobject);
Procedure Formdestroy (Sender:tobject);
Procedure Formpaint (Sender:tobject);
Procedure Button1Click (Sender:tobject);
End
Var
Form1:tform1;
Implementation
{$R *.DFM}
Uses Gdipobj, Gdipapi, Math;
Var
Img:tgpimage;
Procedure Tform1.formcreate (Sender:tobject);
Begin
{Adjust DrawGrid1 display effect}
With DrawGrid1 do
Begin
Align: = Alright;
Width: = 180;
Fixedcols: = 0;
Fixedrows: = 0;
Defaultcolwidth: = 10;
Defaultrowheight: = 10;
ColCount: = 0;
ROWCOUNT: = 1;
Defaultdrawing: = False;
ScrollBars: = Ssnone;
End
Button1.left: = Clientwidth-drawgrid1.width-button1.width;
Button1.top: = 0;
IMG: = tgpimage.create;
End
Procedure Tform1.formdestroy (Sender:tobject);
Begin
Img. Free;
End
Procedure Tform1.formpaint (Sender:tobject);
Var
G:tgpgraphics;
Begin
G: = Tgpgraphics.create (Self.Canvas.Handle);
G.drawimage (IMG, 0, 0, img.) GetWidth, IMG. GetHeight);
G.free;
End
Procedure Tform1.button1click (Sender:tobject);
Var
Palette:pcolorpalette; {Palette pointer}
Colornum:integer; {Total colors in the palette}
Colors:pgpcolor; {color array pointer in palette}
I:integer;
Begin
Opendialog1.filter: = ' All (*.png;*.gif;*.bmp;*.tif;*.jpg) |*.png;*.gif;*.bmp;*.tif;*.jpg ';
If not Opendialog1.execute then Exit;
Img. Free;
IMG: = tgpimage.create (Opendialog1.filename);
Text: = Extractfilename (Opendialog1.filename);
{Allocate memory for palette}
Getmem (Palette, IMG. Getpalettesize);
{Get Palette data}
Img. Getpalette (Palette, IMG. Getpalettesize);
Drawgrid1.colcount: = 0;
Drawgrid1.rowcount: = 1;
If palette^. Count = 0 Then
Begin
ShowMessage (' This picture has no palette ');
Exit;
End
Colornum: = palette^. Count;
Colors: = @Palette. Entries; {A pointer to an array of colors in the palette}
If Colornum < then drawgrid1.colcount: = Colornum Else
Begin
Drawgrid1.colcount: = 16;
Drawgrid1.rowcount: = colornum Div 16;
End
Drawgrid1.refresh; {Do not refresh no}
For I: = 0 to ColorNum-1 do
Begin
DrawGrid1.Canvas.Brush.Color: = Argbtocolorref (colors^);
DrawGrid1.Canvas.FillRect (Drawgrid1.cellrect (i mod, I div 16));
INC (Colors);
End
Freemem (Palette);
End
End.